1. Field of the Invention
Heat- or Fireproofing Coatings.
2. Description of the Prior Art
There is a large body of prior art in the field of the invention and two of the more pertinent prior art references are the following patents:
U.S. Pat. No. 2,901,428 describes fire extinguishing intumescent compositions which may be applied to the fire. These are solid dry chemical fire extinguishing compositions which may also be used as suspensions in water or noncombustible organic liquids. The dry powders include foam forming substances such as phosphoric acids or boric acids and their salts plus finely divided resins which, for example, can be urea formaldehyde resins. Ammonium salts of phosphoric acid are suggested as being especially good. It is stated that in some instances it is desirable to increase the carbon content of the compositions by incorporating carbohydrates, such as starch, sugar, dextrin or cellulosic compounds, or proteinaceous materials, such as glue, casein, gelatin and other glue-like proteins. Also, the compositions may contain inorganic crust forming materials, such as asbestos flour, kieselguhr, gypsum, barite and the like. It is further stated that sodium bicarbonate which is commonly contained in dry chemical fire extinguishers can be included in the compositions and in addition certain other optional materials are suggested. For the dry powder fire extinguishing compositions CO.sub.2 under pressure can be used as a propellant and if in liquid form the composition can be sprayed.
U.S. Pat. No. 3,513,114 describes intumescent coating compositions to provide permanent protective coatings. These compositions are aqueous dispersions comprising water, a polyvinyl acetate latex resin, a solvent plasticizer, a carbonific and a substantially water insoluble ammonium polyphosphate. The carbonifics are urea formaldehyde resins, but the patent goes on to say that non-resinous carbonifics may be used with or in place of the resinous, and these non-resinous carbonifics may include carbohydrates, modified starches, and similar substances, a water dispersible protein and a gelatin or casein or a polyhydric compound such as hexitols (mannitol), penitols (arabitol), monopentaerythritol, the poly-pentaerythritols and solid chlorinated paraffin wax. In addition, the patent says, improved results can oftentimes be obtained from adding to the non-resinous carbonific an amine compound such as dicyandiamide, urea, melamine, dimethyl urea, glycerine and the like with dicyandiamide and melamine being preferred. A disadvantage of these coatings is that due to the substantial organic content, a substantial amount of smoke is produced when these coatings are exposed to heat and fire. Also the patent states that various other additives may be incorporated into the composition such as dyes, pigments, swelling agents, wetting agents, dispersing agents, fungicides or bactericides and the like.